Refrigerating system



Jan. 12 1926.

W. H. CARRIER REFRIGERATING SYSTEM Filed Sept. 2. 1922 Jan. 12 1926. 1,569,214

w. H. CARRIER REFRIGERATING SYSTEM File p 2. 1 5 Sheets-Sheet 2 Jan. 12 1926. 1,569,214

w. H. CARRIER REFRIGERATING SYSTEM Filed Sept- 2. 1922 5 Sheets-Sheet 5 W4 vwfn rallv Jan. 12 1926.

W H. CARRIER REFRIGERATING SYSTEM Filed Sept. 2, 1922 5 Sheets-Sheet 4 vllplvallrovn Jan. 12,1926. 1,569,214

W. H. CARRIER REFRIGERATING SYSTEM Filed Sept. 2, 1922 5 Sheets-Sheet 5 applications filed by ing Patented Jan. 12, 1926.

UNITED STATES PATENT' OFFICE WILLIS E. CARRIER, 0F ESSEX FELLS, NEW JERSEY, IASSIGNOR 1'0 CARRIER ENGI- NEERING CORPORATION, OF NEWARK, NEW JERSEY- BEFRIGERATING SYSTEM.

Application filed September 2, 1922.- Serial No. 585,899.

To all whom it may concern:

Be it known that I, WiLLis H. CARRIER, a citizen of the United States, residing at Essex Fells, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Refrigerating Systems, of which the following is a specification.

This invention relates to compression refrigerating systems in which a volatile re frigerant liquid is vaporized in an evaporator by heat abstracted from the substance being cooled, and a compressor withdraws the refrigerant vapor from the evaporator and delivers it at a higher pressure to a condenser in which it is liquefied, the. liquefied refrigerant being returned to the evaporator. More particularly, the invention relates to a compression refrigerating system of the general nature disclosed in copending me February 2, 1921, Serial No. 441,87 6 and April 5, 1921, Serial No. 458,679 in which a centrifugal fan, exhauster or pump is employed as the compressor, adapted to handle relatively large volumes of gas at low differences of pressure, and in which a refrigerant is used that has a low vapor pressure and high specific density. The system, as herein disclosed is designed to operate under a vacuum, or below atmospheric pressure, in both the evaporator and in the condenser, although in many respects the invention is not limited to a system in which the condenser operates under a vacuum.

A system of this kind has many and important advantages over the usual compres sion systems, in which a positive reciprocatcompressor is used and which are operated at high pressures, or at pressures above atmospheric pressure. For example, in a centrifugal compressor there are no valves and the compressor can be driven by direct connection to a high speed steam turbine or electric motor. The apparatus is much less cumbersome and is flexible in capacity to variations in demand or load. The heavy, cumbersome iron apparatus, such as necessary in ammonia systems, can be replaced by much smaller and lighter apparatus made of brass, aluminum or other metals having vastly higher rates of conductivity, since refrigerants can be used wh ch re inert and do n t a a k m l perature which will be encountere tions.

I prefer to use dichloroethylene as the refrigerant in this system, because I have discovered that this substance has ideal characteristics for use in a refrigerating system of the present type, particularly for units hav- 111g capacities up to about 150 tons. Dichloroethylene does not freeze at an tem- Its boiling point is about 125 F. It does not attack metals even in the presence of water, but on the contrary, prevents corrosion; it is cheap and can be readily obtained in the required quantities; it is not inflammable; 15 not poisonous; does not have an objectionable odor, and it can be handled like water in open containers. Other refrigerants are, however, adapted for use in systems embodying this invention, among which ma be mentioned for instance, trichloroethylene, ethyl chloride, and carbon tetrachloride.

One object of the invention is to produce an efficient, practical and economical refrigcrating system of the character mentioned. Since the system operates under a vacuum and, therefore, is subject to the leakage of air into the system, it is another object of the invention to provide practical means for continuously purging the system of any air and any water due to condensation of water yapor, A further object of the invention is to improve refrigerating systems in the various other respects hereinafter described and set forth in the claims.

My invention is capable of embodiment in apparatus of various different construc- One such embodiment of the invention is disclosed in the accompanying drawings, others forming the subject of additional applications for patents.

In said drawings:

Fig. 1 is an end elevation, partly in section, of the refrigerating apparatus.

Fig, 2 is a plan view partly in horizontal section thereof.

Fig. 3 is a sectional elevation on an enlarged scale, of the accumulator.

Fig; 4 is a sectional elevation on a still larger scale, showing the air evacuating pump and lubricating and sealing means for the shaft of the refrigerant circulating P P- Fig. 5 is an enlarged, sectional elevation oflthe liquid refrigerant trap or expansion va ve,

Fig. 6 is an enlarged sectional-elevation of the pipe connections for the air evacuating pump.

ig. 7 is a sectional plan VIGWOf the air and waterevacuator or separator.

Fig. 8 is a sectional elevation thereof on line 8-S, .Fig. 7.

Fig. 9 is an enlarged fragmentary sectional elevation of the refrigerant pump.

A represents the evaporator or cooler, B the condenser and C the centrifugal fan or, compressor which exhausts the vaporized refrigerant from the evaporator A and delivers it at a higher pressure to the condenser B. D is a motor for driving the centrifugal fan or compressor, preferably an electric motor or steam turbine directly connected with the compressor shaft. E represents a device. hereinafter called the accumulator, by which any air and water vapor are separated from the refrigerant vapor and evacuated from the system, and which performs other functions hereinafter explained.

The evaporator A is preferably constructed so that the liquid refrigerant is caused to flow in thin films over the surfaces of the tubes or passages through which the water or other fluid to be cooled circulates, these circulating tubes or passages being exposed, that is, not submerged in the refrigerant liquid, whereby the pressure of the vaporizing refrigerant does not have to overcome pressure due to the head of the liquid, and the refrigerant can be evaiorated at a less differencein pressure. he condenser B is of a construction adapted for condensing the vaporized refrigerant, preferably below atmospheric pressure, by means of water at ordinary temperatures.

The compressor C is preferably a multiple stage centrifugal gas compressor. This compressor is provided with novel means (covered in a separate application for patent) which provide a substantially friction less seal for preventing the leakage of air or the loss of'vacuum through the shaft opening of the compressor, and balance the end thrust of the compressor rotor in such a way as to practically eliminate friction due to the thrust. Otherwise the compressor may be of known construction.

In the apparatus as shown in the drawings, the compressor is arranged horizon-- tally between the evaporator and condenser, and'the accumulator E is located between the compressor and the evaporator, being preferably arranged and connected in the system so that the vapor from the evaporator tot-he condenser and'the liquid refrigerant from the condenser to the evaporator both pass through the accumulator, which in addition to its other "functions, thus acts as a heat interchanger. The pump F for circulating the refrigerant-is also preferably located in the lower portion of the accumulator.

The refrigerating apparatus disclosed in this application, as an exemplification of my invention, is constructed as follows The evaporator A consists of an outer, cylindrical shell or casing 11, and tubes 12,

extending lengthwise horizontally 111 the.

header 13 through an inlet connection at 15,

passes through a portion of the tubes to one compartment of. the header 1 1, and.

thence back to the'next compartment of the first header 13, and so on, thus circulating back and forth through the tubes and headers and discharging at the outlet connection 15.

The liquefied refrigerant is delivered to the evaporator by the refrigerant circulating pump F through a supply pipe 16 which enters the evaporator at the bottom of the casing 11, and connects with a bent or looped pipe 17, which encircles the flow tubes 12 in the evaporator. Projecting from the pipe loop 17 above the water circulating tubes 12 are lateral pipes 18 equipped with spray nozzles 18" arranged to spray the liquid refrigerant uniformly over the group or flow tubes 12. These spray nozzles are arranged beneath a hood 19, see Fig. 1, having side walls which depend at opposite sides of the group of flow tubes for confin-' ing the spray and preventing it from being thrown outwardly away from the sides of the group of tubes 12. 20 represents a collecting pan or receptacle which extends beneath the flow tubes 12 to catch the unevaporated refrigerant flowing down off of the tubes. This pan has side walls which extend upwardly outside of the lower portions of the sides of the hood 19 so that the walls of the hood and collecting pan form baffles requiring the refrigerant vapor to pass under the lower edges of the hood, then upwardly and over the upper edges of the collecting pan, and thence downwardly between the collecting pan and evaporator casing to the vapor outlet in a neck or connection 21 at the bottom of the casing. 22

represents a drain pipe for returning the surplus liquid from the collecting pan 20 to the reservoir for the circulating pump F in the accumulator E. The refrigerant supply pipe 16 and the drain pipe 22 both preferably pass through the vapor outlet connection 21 at the bottom of the evaporator casing, the pipe 16 being separablyconnected with the looped pipe 17, and the pipe 22 being disconnected from the collectiiigpan so that the enclosed parts of the evaporatorcan be removed from the evapo rator casing .11. For this purpose, the header 13 is detachably secured to and forms the closure for the adjacent open end of the evaporator casing, while the other header 14, is removably supported and centered in the casing 11. When this header 13 is disconnected and the refrigerant supply pipe 16 is disconnected from the looped pipe 17, the flow tubes 12, together with the spray pipes, inner header 14 and collecting pan 20 can all be withdrawn from the open end of the casing as a unit with the connected header 13. It is not necessary to provide a tight connection between the collecting pan and its drain pipe 22, and preferably the collecting pan is simply provided at its bottom with a nipple 23 adapted to discharge into the open, upper end of the drain pipe, so as to avoid the necessity for disconnecting these parts in order to withdraw the removable, inner parts of the evaporator.

The condenser, like the evaporator, preferably comprises an outer shell or casing 24, and a plurality of flow tubes 25, for the water or cooling medium, which extend horizontally within the casing and are connected at their opposite ends to opposite headers 26 and 27. The header 26 is detachably connected to and closes one end of the casing 24, and the other header 27 is removably centered and supported within the shell or casing 24, so that by detaching the header 26, the tubes with their connected headers can be removed as a unit from the shell or casing 24. The headers are made with circular partitions dividing each header into a plurality of annular compartments, and the tubes join these annular compartments 28 of one header with the compartments 29 of the other header in such a manner that the cooling medium flows from the header 26, first through a central group of tubes to the central compartment 29 of the header 27, and thence back through the next outer, annular series of tubes to the next compartment 28 of the header 26, continuing to flow back and forth through the tubes and headers, and discharging from the outermost compartment of the header 26. This header is provided with a radial passage 30 extending from the water inlet connection 31 to the central compartment of this header, and with a discharge connection 32 for the water from the outer compartment 28. 33 represents annular bafiles which extend from the header 26 toward and terminate short of the opposite header 27, and 34 represents a similar bafile extending from the header 27 toward the header 26 be tween the battle plates 33." These 'baflles form'annular spaces communicating with each other alternately at opposite ends of the condenser, through which the vapor is forced to pass in succession back and forth lengthwise over the flow tubes of the con denser. The vaporized refrigerant enters the condenser through air-inlet connection 36 near one end of the lower portion of the condenser casing, and flows through the annular vapor spaces from the outermost space to the space within the central bathe a. Thus, the cold, condensing medium first enters the central group of tubes, and the vaporized refrigerant, after passing in succession over the other annular groups of tubes, then contacts with the central group of tubes which are the coldest. A small volume of vapor is withdrawn from the center of the condenser, as hereinafter explained, thus creating an active circulation of the vaporized refrigerant to the central space containing the coldest condensing 1 tubes. By this construction, the central, coldest group of tubes forms in effect a secondary condenser from which vapor, together with any air therein is withdrawn and purged from the system, as hereinafter explained.

Within the vapor inlet connection 36 of the condenser is arranged a nozzle 37, through which the vapor is delivered into the condenser casing, and'which expands in opposite directions from a contracted waist portion, in the manner of a Venturi tube. he top wall of this nozzle 37 is provided with perforations 38, and flanges projecting upwardly from the sides of the nozzle form a shallow trough 39 on top of the nozzle. The liquefied refrigerant dripping off of the condensertubes, flows into this trough and through the perforations 38 into the vapor nozzle 37. The vapor passing through the nozzle 37 at high velocity vap'orizes enough of this liquid to substantially saturate the vapor, and this has a cooling effecton the vapor, thereby materially reducing the work of condensation demanded of the condenser. 40 represents a collecting pan located within the condenser beneath the water tubes to catch the liquefied refrigerant dripping off of the tubes. This pan is arranged to deliver the liquid into the trough 39 on top of the vapor supply nozzle 37. The collecting pan, as shown in Fig. 1, is arranged and formed so that its bottom forms, in effect, a continuation of the top of the vapor delivery nozzle 37, extending beneath the condensing tubes, but the pan is disconnected from the nozzle in order to enable the pan, which is suitably supported within the condenser casing, to be removed from the cats ing with th condenser tubes when the latter are withdrawn. While the evaporator and condenser are preferably constructed as described, these devices could be of other con-. strnotion without departing from the scope of my invention.

Tilt) The accumulator shown has a casing 41, the lower end of which forms a reservoir for the liquid refrigerant, andthe circulating pump F for the refrigerant is preferably submerged in this body of liquid refrigerant in'the accumulator. A pipe 42 for returning the liquefied refrigerant from the condenser to the pump F, preferably delivers the liquid into a receiving chamber 43 from which it is trapped into the pump reservoir, the receivingchamber being located centrally in the accumulator casing between the vapor inlet and outlet connections 44 and 45 at opposite sides of the casing 41, and connecting the accumula\ tor respectively with the evaporator A and with the compressor C. 46 represents a tank below the condenser into which the liquefied refrigerant drains from the condenser, and with which tank the return pipe connects, thereby preventing the liquid from accumuletting in the condenser. The level of the liquid in the tank can be indicated by any suitable means, such as a gage glass 47. From the receiving chamber 43, the liquefied refrigerant is discharged into the bottom of the accumulator casing through a suitable trap or float-controlled valve 48. As shown best in Fig. 5, this valve is movably mounted in a pipe 49 depending from the receiving'chamber 43 and cooperates with a seat surrounding a discharge opening 50 in the bottom of the receiving chamber 43 to control the discharge of liquid therefrom. The valve has a stem guided in the pipe and connected to a pivoted arm 51 carrying a float 52 which floats on the liquid refrigerant in thebottom of the accumulator casing, thereby maintaining a substantially constant level of the liquid refrigerant in the accumulator and insuring that the intake open- 1 ing of the pump F will always be submerged in the liquid. Any other suitable sort of device for this purpose could be employed.

The pump F delivers the liquid refrigerant to the evaporator through the sufpply pipe 16. The pump F maybe a centri ugal or rotary pump of any construction adapted to handle the refrigerant. If an ordinary centrifugal pump F, such as illustrated in the drawings, is employed, it is better to supplement the same by means adapted to prevent the impaction, or choking of the pump outlet a-ndconsequent impeding of the discharge of the liquid by reason of vapor pressure due to the boiling-of the liquid. For this purpose, a rotary impeller or auxiliary pump 53 is shown, see Fig. 9. This impeller consists of a plurality of parallel, spaced annular plates 54, supported b and projecting inwardly from a surroun ing cylinder or shell 55 which is secured by a disk or wheel 56 at its lower end to the P p S f 57, The plates 54 occupy planes perpendicular to the axis of rotation of the lnipeller and pump, and their-inner edges, which are disconnected, surround a central, open space WhlCll communicates with the inlet 0 ening 58 of the chamber in 7 which the impe ler rotates. The liquid entering the space surrounded by 'the plates is propelled by. centrifugal force through the narrow spaces between the plates and discharges through slots in the cylinder 55 be- 7 tween the plates into the surroundin space 59 in the impeller casing, from whlch the liquid passes to the inlet of the rotor of the centrifugal pump F. 60 represents diffusion blades in the inlet of the impeller 89 and 60 diffusion blades between the impeller 53 and the pump F to prevent rotation of the liquid as it is delivered to the rotor of the pump F.

' The following means are shown for purging from the system any air which may leak thereinto:

61, Figs. 3 and 4, represents an evacuating pump which is operatively connected with the condenser B, where the air collects, 90

in such manner that .a small volume of refrigerant vapor, together with any air that may be present therein, are withdrawn from the condenser, the vapor bein condensed and returned to the system w ile the air and any water resulting from water vapor in the air are separated from the refrigerant and evacuated from the system, as hereinafter explained. The pump 61 shown for this purpose is a rotary pump of known type, in which a liquid piston or body of liquid circulated by the pump operates as the medium for pumping or compressing air orgas, and in the present arrangement a circulating portion of the liquid refriger- 1 ant is utilized as the. compressing medium. A pump of this nature is shown in my appli-" cation, Serial No. 441,376. This evacuating pump is preferably arranged within the accumulator. with-its rotor secured to the shaft 57 of the refrigerant pump F. For the sake of clearness, the pump 61 will hereinafter be called the evacuator pump. The intake of the evacuator pump is connected by a pipe 62 with the condenser B at its central or secondary condensing portion so that the pump 61 is adapted to exhaust the dense vapor, together with any air contained therein from the condenser. The

discharge pipe 63 of the evacuator pump delivers refrigerant liquid through a pipe 65 to the suction pipe 62 of the evacuator pump. Preferably the discharge pipe 65 extends upwardly in the accumulator casing and connects with a passage 66 in the t p f the casing communicating with the suction pipe 62. In this passage is a remov able plug or valve 66" Fi 6, provided with I small holes through whic the liquid asses and which determine the volume of iquid delivered to the evacuator pump. The plug can be removed and the size of the holes therein altered if necessary to insure the delivery of exactly the required quantity of liquid, and when the plug is replaced, the predetermined delivery will remain constant. Thus, when the fiow of the liquid has been once properly regulated tothe required. volume, the flow remains uniform and is not apt to be changed, as might hap-- pen with the use of an adjustable valve.

The evacuator pump discharges the liquid and "apor through the pipe.63, which is provided with a check valve 67, into the separating chamber 64, suitable bafiles68 and 69 being preferably provided in the si-wparator chamber in position for the liqu d to impinge against them, whereby the liqnid is intercepted and caused to fallto the bottom of the chamber, being thus separated from the air and vapor. This chamber is divided by a dam or vertical Wall 70 into inlet and outlet compartments 71 and 72 respectively, which communicate through one or more openings 73 in the bottom of the drun. In the outlet compartment 72 is a weir or wall 73 extending up from the bottom of the compartment and over which the liquid must flow to reach the outlet 74 from the separator. 75 represents a water compartment in the separator, this compartment in the construction slrown being located centrally in the separating chamber and separated from the other compartments by an upright wall 76 which forms a weir over which water must flow to enter the water compartment 75. The edge 77 of this weir over which the water flows is at an elevation somewhat higher than the upper edge of the weir 73. 7 S is an air or water escape pipe leading from the lower portion of the water compartment to the atmosphere. If no air is present in the vapor withdrawn from the condenser B by the evacuator pump, then nothing but the liquid refrigerant is discharged into the separating chamber because all of the 'vaporwill be condensed, since the pressure is at or onlyslightly above atmospheric pressure in the separating chamber, and the pressure of the vapor at the temperature at which it is deliveredis only about 4. or 5 inches of mer-- cury absolute, when using dichloroethylene;

If. however, air is present, the excess vapor only will be condensed out, leaving the residual air saturated with vapor at that temperature and pressure, which will give a relatively small quantity of vapor per weight of air. This air is forced out through the air escape pipe 78 leading from the water compartment 75. As this air is only air that leaks into the system from the outside, due to (p orous castings, or imperfect joints, and is ischarged at a temperature somewhere around 35 or 40 F., 1t is obvious that the moisture in the air will con-' dense out in the discharge pipe of the evacuator pump. Condensation will not-occur at any point in the refrigerating system because the vacuum which exists 1s sufiicient to prevent even saturated air from precipitating moisture. On the other hand,

where it comes to atmospheric pressure and at I low temperature, 1 as in the separating chamber 6d, the moisture will condense out in excess of the normal dew point of 35 or 40'degrees. The water of condensation being lighter than the liquid refrigerant, will float on top of the same and it is separated or skimmed off ofthe refrigerant over the ,upper edge 77 of the weir 76. Since the weir 73 maintains a constant level of the refrigerant, corresponding to the height of this weir, the outlet compartment 72 in which the weir 73 is located will contain water compartment so that any excess accumulation of water is prevented inasmuch as the water will be blown out with the air through the-escape pipe. Water cannot accumulate in the Water compartment above the bottom of the escape pipe.

The suction pipe 62 of the evacuator ump, where the vapor fromthe condenser and the cold liquid refrigerant from the pipe 65 mix, forms another condenser for the vapor wherein the condensation is performed at the expense of the refrigerating effort of the system, .and the discharge pipe .63 of the evacuator pump constitutes still another condenser. Therefore, the refrigerant vapor, which undergoes successive condensations in the primary and secondary portions of the condenser B, is further condensed before entering the air and water separator. And by the use of the cold liquid refrigerant as the air evacuating medium, as explained, the vapor is subjected in all to at least four successive condensations.

The evacuator pump has no stufling box with solid packing, but is sealed Where its shaft passes through the pump casing by means of aliquid seal p1 ovided by liquid re frigerant supplied through a branch pipe by a float-operated valve 79 which acts as a tra to discharge the liquid when it accumu ates above a predetermined level 1n the .outlet compartment 72. The valve 79 is shown asconnected to a pivoted arm 81 prpvi-ded with a float 82 adapted to float on the liquid ,refri erant in the outlet compartment 72. T is float valve always maintains a liquid seal above the outlet open ng 74 so that it is possible to maintain atmospheric pressure in the separating chamher 64, although the pressure in the main liquid receivlng chamber '43 is below atmospheric pressure. It is preferred to arrange the separator to discharge into the'rece vlng chamber 43, as shown, but it could, if desired, discharge directly into the pump reservoir in the bottom of theaccumulator casing. The refrigerant liquid flows continually into n the separating chamber through the pipe 6'3, inasmuch as-there is a continuous supply of the refrigerant through the pipes and- 62 to form t e com-"pressing body and seal for the evacuator =pump. This liquid, therefore, must be continuouslytrapped out and returned, as exlaine'd.

The water in the se arator 64 1s kept above the freezing point yreason of position over or adjacent to the refrigerant receiver 43, into which the warm. liquid is delivered from the condenser. 1 The temperature of this liquid will be somewhere near atmospheric temperature, probably from 65 to 85. Thus, it has sufficient heat to keep the separator well'above the freezing temperature even though the latter is located in the accumulator casing and surrounded by gas considerably below the freezing temperature. The exposure of the. upper part of the separator to the surrounding air aids in preventing freezin Since, however, the peripheral wall of t e separating chamber 64 is exposed to the low temperature of the vapor in the accumulator casing, this prevents the refrigerant liquid in the separator from warming up to an undesirable point and thus expelling an excessive quantity of refrigerant vapor with the air; The temperature of the refrigerant liquid in the separator will be comparatively low, probably in the nei hborhood of 35 to 45 F. By reason of t e location of the liquid-receiving chamber 43, the liquid therein is cooled'to a considerable extent by the sur- IJOOJIG -rounding; low temperature vapor passing through the accumulator from the evaporator to the compressor. This arrangement tor through which the shaft passes and -wh1ch,contains the bearings and the lubricant therefor- It is desirable to have these bearings kept reasonably warm so that the lubrication will'be better and so that the oil will inot'absorb an excessive uantity of the refrigerant vapor. The oil w en warm does not readily absorb the vapor. On the other hand,- if at is cold, it absorbs the vapor in considerable quantities even though it is under a vacuum. The water compartment being maintained practically filled with air acts as a further insulator to prevent conduction I of heat.

The shaft 57 of the refrigerant pump F and'evacuator pump 61' extends out through the top of the accumulator casing for connection to a suitable drivingmotor 83, supported on the accumulator. This shaft has no stufiin Y box, but is journalled preferably in three arings, a ball bearing 84 at the lower end of a sleeve 85 surrounding the shaft in the receiving chamber 43 and se arating chamber 64, a guide bearing busiiingl86 near the upper end of the sleeve, and a all thrust bearing 87 above the guide bearing. bearings insure the necessary,,exact-, vertical alinement of the .shaft. The bearings are lubricated by oil supplied from a reservoir 88, preferably located on top of the accumulator casing and having a duct 89 leading to the uppermost, or thrust bearing; The guide bushing 86 serves to prevent an excessive flow of oil from the oil reservoir into the chamber of the sleeve 85 which is under the same vacuum as the accumulator casing. Fixed on the shaft beneath the thrust bearing 87 is a valve 90 which isadapted to seat against the upper end of the guide bushing 86 when the machine is not running, and is sealed by the oil f-roin the reservoir 88. The thrust bearing 87 sustains the thrust of the shaft which is upward when operating, by reason of the design of the main refrigerant pump F having its inlet at the top. This upward thrust is considerably greater than the weight of the shaft and the parts carried thereby, so.

, admission of air which would occur should ward pressure against the thrust bearing 87, which is made adjustable by means of a screw bushing 91, so that the exact clearance is maintained. The adjustment also adjusts the running clearance between the valve and the bushing 86 to a minimum to prevent excessive flow of oil and limit the endwise movement of the shaft, which should not exceed about five'thousandths of an inch. This can readily be accomplished by tightening the bushing 91 until the valve 90 is firmly seated and then backing it off a fraction of a turn. When the ma? chine is running, the oil between the Valve seat and the bushing 86 forms a frictionless seal which makes a stufling box unneces sary, and when the machine is not running the valve is held to its seat by the entire weight of the shaft and the parts thereon, thus preventing the flow of oil and also the the oil level be seriously reduced.

The oil flows down from the bearings 87 and 86 throughthe bottom bearing 84 into a centrifugal oil pump 92, the rotor of which is secured to theshaft 57 below the bearing 84. The pump returns the oil to the reservoir 88 through a pipe 93, maintaining a constant circulation of the oil when the machine is in operation. The casing of the oil pump has a central sleeve 94 which surrounds the pump shaft 57 and extends up into an annular chamber 95 formed around the shaft in the hub of the rotor. Openings 96 through the hub of the rotor connect the hub chamber 95 with the rotor chamber of the pump and enable the return of oil from the hub chamber to the rotor chamber, thus preventing theescape of the oil from thepump through its shaft openin a skirt or deflector 97 preferably surrounds the rotor hub above the holes therein so that the oil entering the oil pump through the bearing 84 is deflected away from these holes and prevented from escaping therethrough. The pressure within the shaft sleeve 85 and the accumulator casing is balanced through the tube 98 so that there is no tendency for the vacuum topull the oil through the shaft opening, and the described hub construction of the pump with its equalizing openings 96 therefore prevents the pressure produced by the pump from forcing the oil out through the shaft opening into the accumulator casing.

The operation of the.hereindescribed refrigerating apparatus can be automatically controlled so as to maintain a substantially constant, predetermined temperature of the liquid being cooled in the evaporator, and prevent the liquid from freezing in different ways, such for example as disclosed in my application Serial N 0. 458,679, filed April 5, 1921. One method disclosed in said application is by means of a thermostat which is responsive to the condenser temperature and controls the supply of cooling mediuin to the condenser. Another simple method of control explained in said application is to regulate'the supply of the refrigerant liquid to the evaporator by means of a thermostat 100, Fig. 1, which is responsive to the temperature of the liquid being cooled, and controls a thermostatic valve 101 in the refrigerant supply pipe 16 for the evaporator A, through the medium of fluid pressure in'a pipeconneotion 102, or through other suitable operative connections.

The thermostatic valve 101 is adapted to be closed by its spring when the liquid being cooled falls below the predetermined, desired temperature, and the valve is opened more or less to regulate the supply of refrigerant liquid by the action of the thermostat when the tem erature of the liquid being cooled rises al ove a predetermined limit. This control is desirable because when the refrigerant is shut 0E, further refrigeration ceases, since there will be no refrigerant in the evaporator.

1 claim as my invention 1. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it at a higher pressure to the condenser, and means for returning the liquefied refrigerant from the condenser to the evaporator, of means which produces a circulation of a relatively small volume of the liquid refrigerant, means for delivering refrigerant vapor and any noncondensible gas therein from the condenser into said circulating liquid refrigerant, means for frigerant vapor in such circulating liquid to separate it from said noncondensible gas, and means for the escape. of said noncondensible gas from thesystem.

2; In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator and delivers it at a higher pressure to the condenser, and means for returning the liquefied refrigerant from the condenser to the evaporator, of means which produces a circulation of a relatively small volume of the'liquid refrigerant, means for delivering refrigerant vapor and any noncondensible gas therein from thecondenser into said circulating condensing the reliquid refrigerant, and a separating chamber open to the atmosphere through which said circulating liquid refrigerant together with any vapor and noncondensible gas carried thereby passes, whereby the refrigerant "vapor is condensed and separated from said noncondensible gasand said noncondensible gas is discharged from the system.

3. In a refrigerating system employin a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which withdraws the refrlgerant vaporfrom the evaporator and delivers it at a higher pressure to the condenser, and means for returning the liquefied refrigerant from the condenser to the evaporator,

of means which produces a'circulation of a relatively small volume of the liquid refrigerant, means for delivering refrigerant "apor and any noncondensible gas therein from the condenser into said circulating liquid refrigerant, a separating chamber through which said circulating liquid refrigerant together with any vapor and noncondensible gas carried thereby passes, means for maintaining in said chamber a higher pressure and lower temperature than in the condenser, whereby the refrigerant vapor is condensed, and means for the escape of the noncondensible gas from said separating chamber.

4. In a'refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which withdraws the refrigerant vapor from the evaporator-and delivers it at a higher presure to the condenser, and means for returning the liquefied refrigerant from the condenser to the evaporator, of means which produces a circulation of a relatively small volume of the liquid refrigerant, means for delivering refrigerant vapor and any noncondensible gas therein from the condenser into said circulating liquid refrigerant, a separating chamber through which said circulating liquid refrigerant together wth any vapor and noncondensible gas carried thereby pass, means for maintaining in said chamber a higher pressure and lower temperature than in the condenser, whereby the refrigerant vapor and any water vapor carried with said liquid refrigerant are condensed, means for skimming the water of condensation from the liquid refrigerant, and means for the escape of the water of condensation from said separating chamber.

5. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor,

a compressor which withdraws the refriger-,

ant'vapor from the evaporator and delivers it at a higher pressure to the condenser, and means vfor returning the liquefied refrigerant from the condenser to the evaporator, of a pump and liquid circulating system arranged to circulate a relatively small volume of edld refrigerant liquid and withdraw refrigerant vapor and any noncondensible gas therein from the condenser, and deliver the same under pressure into said circulating refrigerant, whereby the refrigerant'vapor is condensed and separated from said noncondensible gas, and means for the escape of said noncondensible gas from the system.

6. A refrigerating system in which a volatile liquid refrigerant is vaporized, the refrigerant vapor condensed and the liquefied refrigerant returned to be again vaporized, including a condenser having provision for condensing the refri 'erant vapor in a partial vacuum, means for withdrawing vapor and any noncondensible gas therein from the condenser and compressing the same, means for cooling said vapor and noncondensible gas at the expense of the refrigerating effort of the system to condense therefrigerant liquid therefrom, means for returning the condensate to the system, and automatic means for discharging the residual vapor and the noncondensible gas mixed therewith from the system.

7. A refrigerating system-in which a volatile liquid refrigerant 1s vaporized, the vapor condensed and the liquefied refrigerant returned to be again vaporized, including a condenser having provision for condensing the vapor in a partial vacuum, means for withdrawing vapor and any noncondensible gas therein from said condenser, another condenser in which the mixed vapor and noncondensible gas are cooled-at the expense of the refrigerating effort of the system to condense the refrigerant from said noncondensible gas and means operating auto m'aticall'y during the operation of the system for returning the condensate from said last condenser to the system, and permitting the escape of said noncondensible gas from the system.

8. A refrigerating system in which a volatile liquid refrigerant is vaporized, the

vapor condensed and the liquefied refrigerant returned to be again vaporized, including a primary condenser having provision for condensing the vapor in a partial vacuum, means for withdrawing condensed vapor and any noncondensible gas therein from said condenser and compressing the same to or above atmospheric pressure, a condenser through which said vapor and noncondensible gas pass and Where the same is subjected to a lower temperature than in the first mentioned condenser to condense refrigerant liquid therefrom, and means operating automatically during the operation of the system for returning the condensate to the system and permitting the escape of the noncondensible gas from the system.

9. A refrigerating system in which a volatile liquid refrigerant is vaporized, the vapor condensed and the liquefied refrigerant returned to be again-vaporized, ln'cludm a condenser having provision for condensing the vapor in a partial vacuum, a device which withdraws vapor and any noncondensible gas therein from said condenser and compresses the same, means for coohng the compressed vapor-and noncondensible gas atthe expense of the refrigerating effort of the system to condense the refrigerant vapor out of the mixture, means for condensing the vapor at the suction side of said device at the expense of the refrigerating effort of the system to increase the capacity of said device, and means for separating the condensate from the air and returning the condensate to the system.

10. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a centrifugal compressor which delivers the refrigerant vapor from the evaporator to the condenser and mamtains a pressure below atmospheric pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator, of means for withdrawing refrigerant vapor and any noncondensible gas therein from the condenser, means for cooling said vapor and noncondensible gas by means of a medium cooled by the system for condensing the vapor out of the mixed noncondensible gas and vapor, and automatic means for permitting the escape of said noncondensible gas from the vsytsem and returning the condensate to the system.

11. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the li uid r frigerant, a condenser for the re rigerant vapor, a. compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospheric pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator, of an air and refrigerant vapor separating device, means for withdrawing refrigerant vapor and any air therein from the condenser and compressing the same into said separating device, means for maintaining in said separating device a higher pressure and a lower temperature than in the condenser, whereby vapor is condensed out of the mixed air and vapor, means for the escape of said air from said separating device, and means for returning the condensate to the system.

12. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid'refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains pressures below atmospheric pressure in both the evaporator and condens er, and means for returning the liquefied refrlgerant from the condenser to the evaporator, of means for withdrawing refrigerant'vapor and any noncondensible gastherein from the con' enser, means cooled by the cooling action of said evaporator at the expense of the refrigerating effort of the system for condensin the vapor out of the mixed noncondensi le gas and vapor, and automatic means for permitting the escape of said noncondensible gas from the system 2nd for returning the condensate to the sys 13. A refrigerating system in which a volatile liquid refrigerant is vaporized, the vapor condensed and the liquefied refrigerant returned to be again vaporized, includmg a condenser having provision for condensing the vapor in a partial vacuum, a compressor which withdraws vapor and any noncondensible gas therein from said condenser and compresses the same to or above atmospheric pressure, means for condensing the vapor at the suction side of said compressor at the expense of the refrigerating effort of the system to increase the capacity of said compressor, and means for separating the condensate from the noncondensible gas and returning the condensate to the system. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant 100 vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospheric pressure in the evaporator, and means for returning the liquefied refriger- 10 ant from the condenser to the evaporator, of a refrigerant vapor and air separating chamber, an evaouator pump in which a body of the cold liquid refrigerant forms a vapor compressing medium and which draws 1 refrigerant vapor and any air therein from the condenser and delivers the same together with liquid refrigerant to said separating chamber whereby said refrigerant vapor is condensed, means for the escape of said air 115 from said separating chamber, and means for returning the liquid refrigerant from the separating chamber to the system.

15. In a refrigerating system employing a volatile liquid refrigerant, the combina- 12( tion with an evaporator for the liquid refrigerant, a condenser for the refri erant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below 125 atmospheric pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator. of a refrigerant vapor and air separating chamber, an evacuator pump and connections which draw refrigerant vapor and any air therein from the condenser and forcethe same under pressure together with a portion of the cold hquid refrigerant to the separatmg chamber whereby said refngerant vapor is condense means for the escape of said air from said separating chamber, and means for returning the liquid refrigerant from the separating chamber to the system.

16. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which dehvers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospheric pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator, of a refrigerant vapor and air separating chamber, an evacuator pump and connectlons which draw refrigerant vapor and any air therein from the condenser and force the same under pressure together with a portion of the liquid refrigerant to the separatin chamber, means for supplying cold refrlgerant liquid to the vapor and air connection at the suction side of said evacuator pump to condense the vapor prior to its compression by said pump, means for the escape of air from said separating chamber, and means for returning the liquid refrlgerant from the separating chamber to the system.

17. In a refrigerating system employing a volatile liquid refrigerant,'the combmation with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospherlc pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator, of a refrigerant vapor and air separating chamber provided with an air escape opening and a liquid refrigerant outlet, an evacuator pump and connections which draw refrigerant vapor and any air therein from the condenser and force the same under pressure together with a portion of cold liquid refrigerant into said separating chamber, whereby said refrigerant vapor is condensed and said air escapes from said separatin chamber, and a liquid refrigerant trap for sealing the liquid outlet of said separating chamber and returning the liquid refrigerant to the system.

18. In a refrigerating system employin a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospheric therein from the condenser and delivering the same together with liquid refrigerant to said separating chamber, a weir in said separating chamber over which the liquid flows from the liquid inlet to the liquid outlet, a water compartment in said separating chamber, a second weir higher than said first weir over which any water on said liquid refrigerant flows into said water compartment, an opening from said Water compartment to the atmosphere, and means for permitting the discharge of liquid refrigerant through said outlet.

19. In a refrigerating system employing a volatile liquid refrigerant, the combinat on with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser and maintains a pressure below atmospheric pressure in the evaporator, and means for returning the liquefied refrigerant from the condenser to the evaporator, of a refrigerant vapor and air separating chamber having a liquid inlet and liquid outlet, means for drawing refrigerant vapor and any air therein from the condenser and delivering the same together with liquid refrigerant to said separating chamber, a Wall dividing said separating chamber into inlet and outlet compartments which communicate at their lower portions, a water compartment in said separating chamber, a weir in said outletcompartment over which the liquid refrigerant flows to the. liquid outlet, a second weir between said inlet and water compartments over which any water on the liquid refrigerant flows into the water compartment, an opening from said water compartment to the atmosphere, and means for permitting the discharge of liquid refrigerant'through said outlet.

.20. In a refrigerating system employing a volatile liquid refrigerant, the combinatlon with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser .and maintains a pressure below atmospheric pressure in the evaporator, and means for returningthe liquefied refrigerant from the condenser to the evaporator, of a refrigerant vapor and air separating chamber having a liquid inlet and liquid outlet, means for drawing refrigerant vapor and any air therein from the condenser and delivering the same together with liquid refrigerant to said separating chamber, a water compartment in said separating chamber, means for separatpressure in the evaporator, and means for ing any water from the liquid refrigerant and delivering it into said water compartment, a pipe. leading upwardly from the lower portion of said Water compartment to the atmosphere, and means for permittm the discharge of liquid refrigerant througi said liquid outlet.

21'. I11 a refrigerating system employing a volatile liquid refrigerant, the combination of an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor -which delivers the refri erant vapor from the evaporator to the con enser, an accumulator casing through whlch the refrigerant vapor passes from the evaporator to the condenser, a liquid refrigerant circulating pump in said accumulator casing, a

liquid receiving chamber in the accumulator casing which receives the liquefied refrigerant from the condenser, and means for trapping the liquid refrigerant from sald receiving chamber into the accumulator caslng for circulation by said pump.

22. In a refrigerating system employing a volatile liquid refrigerant, the combination of an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser, an accumulator casing through which the refrigerant vapor passes from the evaporator to the condenser, a liquid refrigerant circulating pump in saidaccumulator casing, said pump having a driving shaft extending out of said accumulator casing, a liquid receiving chamber in said accumulator casing surrounding said pump shaft and having a bearing sleeve in which the shaft is yournalled, a connection for returning the liquefied refrigerant from the condenser to said receiving chamber, and means for trapp ng the liquid refrigerant from said recelvmg chamber into the accumulator casing for circulation by Said pump.

23. In a refrigerating system employlng a volatile liquid refrigerant, the combmatlon of an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser, an accumulator casing through which the refrigerant vapor passes from the evaporator to the condenser, a. liquid refrigerant circulating pump in said accumulator casing, a liquid receiving chamber in the accumulator which receives the liquefied refrigerant from the condenser, means for trapping the liquid refrigerant from said receiving chamber into the accumulator casing for circulation by said pump, a refrigerant vapor and air separating chamber arranged adjacent to said liquid receiving chamber, means for delivering refrigerant vapor and any air therein from the condenser together with cold li uid refrigerant to said separating cham er, means for the escape of air from said separating chamber, and means for returning the liquid refrigerant from said separating chamber to the system.

24. In a refrigerating system employing a volatile liquid refrigerant, the combination with an eva orator for the liquid refrigerant, a cond nser for the refrigerant va )or, and a compressor which delivers the re rigerant vapor from the evaporator to the condenser, of a casing to which the liquefied refrigerant is returned from the condenser, a rotary pump in said casing for delivering the liquid refrigerant to the evaporator, a refrigerant vapor and air separating device, and a rotary evac'uator pump in said casing and arranged to deliver refrigerant vapor and any air therein from the condenser to said separating device, said pumps having a common drive shaft extending out of said casing.

25. A refrigerating system in which a volatile liquid refrigerant is vaporized, the vapor condensed and the liquefied refrigerant returned to be again vaporized, including a condenser having provision for condensing the vapor in a partial vacuum, a device which withdraws vapor and any noncondensible gas therein from said condenser and compresses the same to or above atmospheric pressure, means for cooling the compressed vapor and nonconden'sible gas at the expense of the refrigerating effort of the system to condense the refrigerant vapor out of the mixture, and automatic means for separating the condensate from the noncondensible gas and returning the condensate to'the system.

26. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the liquefied refrigerant is returned from the condenser, a pump in said casing for delivering the liquid refrigerant to the evaporator, a pump shaft, bearings for the pump shaft, and means for passin the warm liquid refrigerant from the con enser to the pump in proximity to the pump shaft hearings to Warm the lubricant for said bearings.

27. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, a compressor which delivers the refrigerant vapor from the evaporator to the condenser, and a pump for returning the liquefied refrigerant to the evaporator, of a refrigerant vapor and air separating device,

means for drawin vapor and any a1r therein from the con enser and delivering thesame under pressure to said separating device, means for circulatmg a portion of the cold liquid refrigerant through said sepaerant vapor from the evaporator to the conrating device for condensing and separating said vapor from said air, and means for passing the warm liquid refrigerant returning from the condenser in proximity to said separating device to prevent freezing there- 1n.

28. In a refrigerating system. employing a volatile liquid refrigerant,"the combination with an evaporator for the liquid refrigerant, a condenser -for the refrigerant vapor, and a compressor which deliyers the refrigerant vapor from the evap'orator'tothe 'condenscr,of a casing towhich the lique fied refrigerant is returned from the condenser, a pump in said casing for delivering the liquid. refrigerant to the evaporator, a pump shaft extending out of said casing, an

oil seal for the opening through which the.

shaft passes, means for circulating oil through said seal, and means for passing the .warm liquid refrigerant returning fromthe condenser in proximity to said oil seal to warm the oil.

29. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a -condenser for the refrigerant vapor,'and a compressor-which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the liquefied refrigerant is returned from the condenser, a pump in said casing for deliveringihe liquid refrigerant to the evaporator, a pump shaft extending out of said casing, an oil seal for the opening through which the shaft passes, bearings for said shaft, means for. circulating oil through said seal and bearings, and means for passing the warm liquid refrigerant returning from the condenser in proximity to said oil seal and bearings to warm the oil.

30. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor,-

and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a'casing to which the liquefied refrigerant is returned from the condenser, a rotary pump in said casing for delivering the liquid refrigerant to the evaporator, a

rotary evacuator pump in said casing for and a compressor which delivers the refrigdenser, of a casing to which the liquefied" refrigerant is returned from the condenser, a pump in said casing for delivering the liquid refrlgerant to the evaporator, a pump shaft extending out of said casin a liquid seal for the opening through which the shaft passes, and a valve which automatically seats to close said opening when said pump stops.

32. In a refrigerating system employing a volatile liquid refrigerant, thecombination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the li uefied refrigerant is returned from thereon enser, a pump in said casing for delivering the liquid refrigerant to the evaporator, a pump shaft extending out of said casing, a liquid seal for the opening through which the shaft passes, and a valve which is held unseated .bythe end thrust on said shaft when the pump is in operation and is seated by the Weight on said shaft to close said opening when said pump stops.

- 33. In a refrigerator system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor, and a compressor which delivers the refrigerant vapor from the evaporator to the condenser,-of a casing to which the li uefied refrigerant is returned from the con enser,

a centrifugal pump for the liquid refrigerant submerged in the same in said casing, and a rotary impeller for delivering 'the li uid refrigerant to said centrifugal pump, sald impeller comprising a plurality of spaced annular disks arranged perpendicularly to their axis of rotation and disconnected at their inner edges.

34. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor,

and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the li uefied refrigerant is returned from the con enser, a centrifugal pump for the liquid refrigerant submerged in the same in said casing, and a rotary impeller for delivering the liquid refrigerant to said centrifugal pump, said impeller comprising a plurality of spaced annular disks surrounding and connected to the shaft of said centrifugal pump perpendicular thereto, said disks being d1sconnected at their inner edges 'and submerged in the liquid refrigerant in advance of the intake'of said centrifugal pump.

35. In a refrigerating system employmg a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerunit, a condenser for the refrigerant vapor,

and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the liquefied refrigerant is returned from the condenser, a rotary pump in said casing for deliverin the liquid refrigerant to the evaporator, an

-connections whereb' the refrigerant vapor passes through sai casing from the evaporator to the condenser.

36. In a refrigerating system employing a volatile liquid refrigerant, the combination with an evaporator for the liquid refrigerant, a condenser for the refrigerant vapor,

and a compressor which delivers the refrigerant vapor from the evaporator to the condenser, of a casing to which the liquefied refrigerant is returned from the condenser, a rotary pump in said casing for delivering the liquid refrigerant to the evaporator, connections whereby the refrigerant vapor passes through said casing from the evaporator to the condenser, and a chamber located in said casing in the path of the refrigerant vapor and through which the liquid refrigerant passes from the condenser to said casing.

WILLIS H. CARRIER. 

